This paper investigates the extraction of acoustic signatures from small boats using a passive sonar system. Noise radiated from a small boats consists of broadband noise and harmonically related tones that correspond to engine and propeller specifications. A signal processing method to automatically extract the harmonic structure of noise radiated from small boats is developed. The Harmonic Extraction and Analysis Tool (HEAT) estimates the instantaneous fundamental frequency of the harmonic tones, refines the fundamental frequency estimate using a Kalman filter, and automatically extracts the amplitudes of the harmonic tonals to generate a harmonic signature for the boat. Results are presented that show the HEAT algorithms ability to extract these signatures.

Near-field remote sensing of surface velocity and river discharge (discharge) were measured using coherent, continuous wave Doppler and pulsed radars. Traditional streamgaging requires sensors be deployed in the water column; however, near-field remote sensing has the potential to transform streamgaging operations through non-contact methods in the U.S. Geological Survey (USGS) and other agencies around the world. To differentiate from satellite or high-altitude platforms, near-field remote sensing is conducted from fixed platforms such as bridges and cable stays. Radar gages were collocated with 10 USGS streamgages in river reaches of varying hydrologic and hydraulic characteristics, where basin size ranged from 381 to 66,200 square kilometers. Radar-derived mean-channel (mean) velocity and discharge were computed using the probability concept and were compared to conventional instantaneous measurements and time series. To test the efficacy of near-field methods, radars were deployed for extended periods of time to capture a range of hydraulic conditions and environmental factors. During the operational phase, continuous time series of surface velocity, radar-derived discharge, and stage-discharge were recorded, computed, and transmitted contemporaneously and continuously in real time every 5 to 15 min. Minimum and maximum surface velocities ranged from 0.30 to 3.84 m per second (m/s); minimum and maximum radar-derived discharges ranged from 0.17 to 4890 cubic meters per second (m3/s); and minimum and maximum stage-discharge ranged from 0.12 to 4950 m3/s. Comparisons between radar and stage-discharge time series were evaluated using goodness-of-fit statistics, which provided a measure of the utility of the probability concept to compute discharge from a singular surface velocity and cross-sectional area relative to conventional methods. Mean velocity and discharge data indicate that velocity radars are highly correlated with conventional methods and are a viable near-field remote sensing technology that can be operationalized to deliver real-time surface velocity, mean velocity, and discharge.

SummarySnohomish Public Utility District #1 (SnoPUD) proposes to deploy two OpenHydro tidal turbines in Admiralty Inlet, Puget Sound. The fisheries service of the National Oceanic and Atmospheric Administration (NOAA Fisheries) has expressed concerns that the turbines may cause a risk for the highly endangered Southern Resident Killer Whale (SRKW) population if a whale is struck by an operating turbine. NOAA Fisheries is responsible for protecting the (fewer than 90) SRKWs under the Endangered Species Act and the Marine Mammal Protection Act. Because the SRKW numbers are so small, significant injury of a single animal could place the population in jeopardy.The potential risk to a SRKW can be parsed into the probability that a whale would encounter a turbine, the probability that the encounter would injure the whale, and the severity of any injury. During a meeting with representatives of SnoPUD, OpenHydro, the Department of Energy, and NOAA Fisheries, participants agreed that the probability of a SRKW encountering a turbine by chance is negligibly small as the whales spent greater than 97 percent of their time in Admiralty Inlet in the top 30 meters of water, while the turbines are located at 55 meters of depth, and the SRKW have highly evolved acoustic sensory capabilities that would help them detect the presence of a turbine. NOAA Fisheries expressed concerns over the potential severity of a strike on a SRKW should it occur. A proposed solution was to conduct an estimate of the level of injury that might occur from an encounter between a turbine blade and a SRKW, which would allow NOAA Fisheries to determine the permitting requirements for the tidal project.Pacific Northwest National Laboratory (PNNL) and Sandia National Laboratories (SNL) were tasked by the Department of Energy to carry out an analysis of the mechanics and biological consequences of strike of a SRKW by an OpenHydro turbine blade. The approach taken by the two laboratories was to: 1) develop a scenario for the most severe strike of a SRKW; 2) determine the morphological and biomechanical properties of SRKW tissues that might be affected by a strike; 3) model the forces of a strike; and 4) estimate the potential effects on SRKW tissue and bone of a strike.PNNL and SNL developed a worst case exposure scenario for strike of a SRKW. SNL modeled a turbine blade (based on proprietary design data obtained from OpenHydro), and calculated the force of blade impact on the head of an adult male SRKW, weighing approximately 4000 kilograms. The adult SRKW was selected for the model because an adult has a large body mass where more of the energy in a blade strike will be absorbed by the whale's tissue rather than going into momentum transfer that would push the whale out of the path of the turbine blade. This scenario would maximize the risk of injury to the SRKW. Although a juvenile SRKW might intuitively be considered to be at greater risk of injury, because of much smaller mass (~500 kg) more of the energy in the blade strike would go into momentum trans...

This paper presents a method for passive acoustic detection and tracking of small vessels in noisy, shallow water marine environments. Passive spectra of boats include broadband noise as well as tones that are harmonics of the engine speed and shaft/propeller rotation. Past work suggests that the location in frequency and the relative amplitudes of these harmonics can be used to determine specific characteristics of the vessel such as the number of blades on the propeller and engine type/speed. However, the low signal to noise ratio of quiet targets and Doppler shifts incurred because of source and receiver motion complicate the identification of these tones in the lofargram. To address this issue, a combined detection and tracking approach is proposed in which intermittent and wandering harmonic content is tracked with a multi-dimensional Kalman filter. Results from recorded passive signatures from several classes of vessels in marine and freshwater environments in the Pacific Northwest are presented and discussed.